1. Field of the Invention
This invention relates to panoramic photography systems, and to the creation of images by means other than lenses. It is also related to signal processing devices for composite video recording.
2. Description of the Prior Art
Panoramic photography, to encompass a wider field of view, has been attempted with many systems, both for film and for video cameras. For example, fisheye lenses may be used on cameras to record a hemispherical field of view in a single exposure.
However, to gain greater overall resolution and more control over separate sections of the image, multiple exposures can also be used to create a composite wide-angle image. Many systems of composite image panoramic photography have been attempted. An optimum system would be based upon a simple standard picture shape, with equal edges, and a simple and consistent organization that lends itself to a variety of formats and applications. These qualities are characteristic of the dodecahedral imaging system described in the Applicant's U.S. Pat. No. 5,023,725, "Method and Apparatus for Dodecahedral Imaging System" (European patents pending) here called the Dodeca.TM. System, and also known as RoundAbout.TM. Immersive Imaging.
The Dodeca System uses the structure of the pentagonal dodecahedron to determine the angles of view and alignments for both cameras and projectors to produce pentagonal images; by adding together these pentagonal images, one can present a wrap-around spherical image with high resolution, freedom from distortion, and lack of visible seams. By overlapping pentagonal images taken from different points of view, stereoscopic effects can also be produced.
In this earlier patent, camera and projection systems are described based on single-pentagon, dual-pentagon and triple-pentagon views, as well as an electronic viewfinder, consisting of multiple camera views held contiguously in a virtual frame store, and viewed through a mobile viewing window controlled by the operator. The present application gives details and improvements for each of these systems.
Wrap-around computer image displays, whether stereoscopic or not, are found in advanced scientific and technical applications, from designing buildings and molecules to envisioning weather patterns. These displays are especially effective when viewed through a head-mounted display that can track the direction of the gaze of the viewer and react accordingly, giving one the impression of being surrounded by the computer-generated world. This has given rise to a growing number of applications in games and entertainment. These wrap-around stereoscopic environments, usually viewable by head-mounted displays, are usually described under the label of "virtual reality," or simply VR.
These VR displays to date have not included images of the real, photographable world; instead, the environment is entirely artificial, and has to be continuously regenerated in response to the direction of the gaze of the viewer and his or her interactions with it. This typically requires a great deal of expensive computer power, and there is always a lag in response corresponding to the complexity of the illusion being regenerated. A completely realistic computer-generated wraparound environment is a daunting challenge. Almost no computer can approach the complexity and subtlety of the appearance of the real world. The long labors of the most skilled programmers, on the most powerful computers, are needed to approach the level of complexity and subtlety visible in even a simple snapshot.
The lack of an efficient method for bringing wrap-around images of the external world into VR displays has led to a focus on artificially-generated environments, making a scene more difficult to construct and leading to an unconvincing result. To artificially create a stereoscopic, real-looking scene in full motion (30 frames per second), while retaining instant response to the gaze of the viewer in a head-mounted display, is beyond the current state of the art in VR technology.
Attempts at panoramic recording of external scenes for a wrap-around environment have been made for flight simulators, to show the landscape a trainee is flying over. For example, Y. P. Chen, in the magazine ESD for February 1988, reports the recording of a data base of hemispherical images by means of a custom-built array of seven cameras simultaneously exposing portions of the field of view onto 9-inch wide film; the resulting film images were scanned, then electronically color-corrected, and mapped to create a composite fisheye view. These fisheye views are taken in rapid sequence, sufficient to create an impression of motion. However, the images are not all the same size and shape, seven cameras are required for a hemispherical view, the recording medium is not standard, and extensive digital processing of the images is required to make them suitable for display. With a dodecahedral system, on the other hand, all the component images are of the same shape and size, a hemispherical image can be captured with six cameras or less, a standard recording medium such as video is used, and almost no processing of the image other than cropping is required for display.